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I have just become the proud second owner of a Don Allen preamp. Mine is a fairly late 2 tube build, from sometime in 2015. According to postings here on Audioasylum that might be just before Don retired and moved to Florida.
I am posting this message to attempt to collect in one place useful information about the various versions of the two and four tube line level preamp that were produced over the years. Without a standing website, I think it will be a useful exercise.
The following are a few observations/questions to get the ball rolling.
Does the unit invert phase? I have it hooked up as non-inverting and it sounds fine, but I do plan to try it both ways. I ask because both my Quicksilver and Mapletree preamps do invert phase.
It shipped to me with ECC85 tubes, but I understood that it was designed for 6BQ7 tubes. What are the experiences of other owners/users? I plan to roll with some very quiet GE 6BQ7s from my Schiit Lyr 2 headphone amp and see which tubes I prefer.
I found an older Audioasylum posting that says that the preamp was designed to best match with power amps rated at an input impedance of 470 Kohms. What are the experiences of other owners/users with matching power amps?
The Rike output caps are rated at 2.2 uF. Is that consistent with the other units from other owners, or has that value varies over the years. I ask this because my local tube guru says that this cap value will change how the preamp interacts with the input impedance of the power amp.
And lastly, my unit has a very nice TKD 100K volume pot. Is that typical of all the units that Don produced?
All you Inmates with experience with Don Allen gear, please post your preamp insights so they can be collected for other owners/users.
Follow Ups:
Thanks for the great responses. The only reference I found to the ECC85 tube was on the Tube World website, where they list that type as recommended for the Don Allen. Chuck now confirms that it works well in his Don Allen preamp.
Several days of searching on the 'Net have turned up photos of versions with both four tubes and two tubes, one bridge rectifier and two bridge rectifiers, four inputs, five inputs, and even a mono switch. Do any other inmates have experience with these versions? Chuck also mentions that the later two tube version will work well with power amp input impedances down to 100K. Good to know for those of us using solid state MOSFET or bipolar transistor amps.
I have the same preamp, I believe from the same "generation." Don told me these newer generation preamps mate well with amps that have input impedances down to 100k ohms. In mine, I prefer the ECC85 tubes to the standard 6BQ7 tubes, although I have not tried every 6BQ7. I am using Tungsram ECC85's. The 6BQ7's are softer, warmer, less detailed. The ECC85's are more detailed but not etched, have better extension at both ends, and have a wonderful tone. Either way, it's a beauty of a pre. I am using mine with an 807 SET amp from Don, and the match is heavenly. Haven't had any desire to change these out for a couple of years. Enjoy!!
Had a Don Allen preamp a few years ago and thought it was wonderful. I added Jupiter flat stack output caps to mine, Alps black beauty volume pot, furutech iec recepitcle with built in emi filter and last but not least Cardas rca connectors to it.....and what a transformation it made!
Thanks! for sharing- Alta _tom
Don Allen gear has quite a following. If there are no fans here, check out Audiogon Forums.
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